Control mechanism for record-cutting heads



March 17, 1964 K. IMMENDORF CONTROL MECHANISM FOR RECORD-CUTTING HEADS *5 Sheets-Sheet 1 Filed June 18, 1962 TUE KARL IMMENDORF INVENTOR.

AGENT March 17, 1964 K. IMMENDORF 3,125,344

CONTROL MECHANISM FOR RECORD-CUTTING HEADS Filed June 1962 3 Sheets-Sheet 2 s :r i f I 32 17 5 12 31 W IF q/ l lllllmfl13 15/ H 11 V//// 45 6 525 L i"" LJ 44 I IITII 1//////// /A a 25 33 T4 36 g g 29- 32 3 2 28 25 T: 26

KARL IMMENDORF INVENTOR.

BY g R AGENT March 17, 1964 K. IMMENDORF 3,125,344

CONTROL MECHANISM FOR RECORD-CUTTING HEADS Filed June 18, 1962 3 Sheets-Sheet 3 K ARL IMMENDORF INVENTOR.

United States Patent 3,125,344 CONTROL MECHANlggAFgR RECORD-CUTTING 4 D Karl Immentlorf, Uberlingen, Germany, assignor to NSM- Apparatebau, G.rn.b.H., Kommanditgesellschaft, Bingen (Rhine), Germany, a company of Germany Filed June 18, 1962, Ser. No, 203,127 18 Claims. (Cl. 274-32) My present invention relates to a control mechanism for a recording head having means to cut spiral grooves in a blank of plastic, metal or other suitable material, the cutting means being modulated (e.g. electromagnetically) in response to acoustic waves for recording a reproduceable sound message on the blank.

The need for reasonably high fidelity in the recording of sounds dictates an accurate synchronization between two disparate drives, one being used to rotate the blank While the other advances the recording head across the blank to cut the desired spiral groove. This groove is generally divided into two distinct parts, namely a smallpitch main portion containing the sound message and a large-pitch lead-01f portion of one or more turns designed to deflect the holding arm of the recording head (or, during playback, of the pick-up head of a reproducer) at an accelerated rate to cut off the drive mechanism. For reasons of economy it is desirable to have both drives powered by a single motor, yet the problem of switching between different pitches of a spiral with maintenance of overall synchronism between the two drives is not easily solved in an inexpensive manner.

My invention, accordingly, has for its general object the provision of a relatively simple means for concurrently controlling the rotation of a recording blank and the generally radial advance of an associated cutting head across such blank in a manner enabling ready switching from one rate of advance to the other.

A more specific ob'ect of the invention is to provide means in a record-cutting system for automatically, shifting from a relatively slow to a relatively fast rate of advance at a predetermined point in the recording cycle, i.e. after completion of a message of standard length, and for enabling such switch-over to be selectively carried out at an earlier stage of the operation upon the recording of a shorter message.

It is also an object of this invention to provide means in such system for so mounting a cutting head on a support therefor as to minimize interferences with and disturbances of the recorded message due to parasitic vibrations, excessive play or poor shock absorption.

An important feature of this invention resides in the provision of a cutting-head drive including a lead screw with a thread having sections of different pitch, in combination with two coupling elements respectively engageable with the small-pitch thread section and the largepitch thread section of the screw under the action of a manual selector for advancing the recording head across the recording blank at a speed depending on the pitch of the engaged thread; one of the coupling elements, if left engaged with the small-pitch thread section of the lead screw, will automatically shift over to the large-pitch thread thereof in a predetermined recording-head position if the manual selector is not actuated before. This selector advantageously also has an extension adapted to earn the last-mentioned coupling element into initial engagement with the small-pitch thread in a motion which causes the cutting of the lead-on turn of the spiral groove.

In a preferred embodiment the two coupling elements are swingable arms of which one, normally spring-urged into engagement with the other, during the recording of the message coacts with the small-pitch thread section of the lead screw; the second arm is connected directly with material, preferably a silicone rubber.

3,125,344 Patented Mar. 17, 1964 ice the recording-head support. When the selector is operated to couple the second arm with the large-pitch thread section, the first arm becomes inoperative even if allowed to remain engaged with the small-pitch thread section. It is this first arm which, according to a more specific feature of the invention, can be manually cammed by the selector to produce the starting turn of the spiral groove.

The invention will be described in greater detail with reference to the accompanying drawing in which:

FIG. 1 is a plan view of a recording apparatus embodying the invention;

FIG. 2 is an enlarged sectional view taken substantially on the line 11-11 of FIG. 1;

FIGS. 3 and 4 are sectional detail views taken on the lines III-lll and IV-IV, respectively, of FIG. 2;

FIG. 5 is a perspective view of part of the internal mechanism of the apparatus seen in FIG. 2; and

FIG. 6 is a circuit diagram relating to the apparatus.

The recorder 10 shown in the drawing comprises a casing 11, a stem 12 projecting from the upper surface of the casing, a platter 13 carried by the stem, a recording arm 14 (preferably of plastic material) swingably positioned on a tubular shaft 15 and provided with a head 16 whose cutting stylus 17 can be swung generally radially across the platter 13, and a selector knob 18 on a shaft 19 having an off position 0 and four alternate positions respectively designated 1, 2, 3 and 4. The electrical connections to the head 16 are included in a flexible cable 2t) passing into the interior of casing 11 through a hole 21 thereof. A slot 22 accommodates a link 23 which is articulated to the arm 14 to codetermine its position, the arm being swingable on a stud 24 which traverses a block 25 on shaft 15. A counterweight 84 balances the arm 14 on its pivotal stud 24.

As best seen in FIGS. 2, 3 and 4, block 25 is straddled by a yoke 26 of U-shaped profile which is fixedly secured to the arm 14 by rivets 27 and has two pairs of lateral slots 28 accommodating respective steel balls 29. These balls are resiliently urged into contact with the sides of the block 25 by spring blades 30 which are anchored to the yoke 26 at 31 (e.g. by spot welding) and are provided with ball-receiving indentations 32 overlying the slots 28. Stud 24, inserted in a narrow bore 33 of block 25 and held in place by split washers 34, also traverses a larger bore 35 transverse thereto in which there is disposed an elastic pad 36 laterally urging the stud 24 against the wall of bore 33. Pad 36 consists of a suitable elastomeric Thus, arm 24 is free to swing in a vertical axial plane of shaft 15 against a very small resistance represented mainly by the rolling friction of the balls 29; the resiliency of the spring blades 30 secures the yoke 26 and thus the arm 14 against lateral excursions. Pad 36 eliminates any play originally existing between the stud 24 and its bore 33.

The tubular shaft 15 extends downwardly into the casing 11 where it traverses a conventional cut-oil switch 37 adapted to respond to an accelerated horizontal swing of the arm 14. At its lower end the shaft 15 surrounds a fixed stem 38 and is fastened to a transport arm 39 swingable about this stern. Another transport arm 40 is journaled on stem 38 for swinging, in a horizontal plane paralleling that of arm 39, about stem 38 independently of shaft 15. Arm 3:9 is urged by a spring 41, anchored to casing 11, in a counterclockwise sense (as viewed from above) whereby a lug 42 on this arm bears upon the arm 46 to entrain it in the same direction.

The stem 12 is coupled with an alternating-current motor 43 which also drives a lead screw 44 through the intermediary of a transmission bolt 45 in engagement with a pulley 46 on stem 12 and another pulley 47 on the shaft 48 of screw 44. Lead screw 44 is formed with a helical groove defining a continuous thread with a small-pitch section 49 and a large-pitch section 50. Arm 40 is provided with a resilient extension in the form of a tongue 51 having a longitudinal slot 52 wherein a coupling pin 53 is slidably mounted with the aid of a collar 54. Arm 39 is similarly provided with a resilient tongue 55 having a slot 56 wherein a coupling pin 57 is slidably held by means of a collar 58. These pins are guided along the top of lead screw 44 between two levers 59, 60 respectively aligned with a hump 61 on tongue 51 and a similar hump 62 on tongue 55. The two levers, urged upwardly by the associated tongues, are fulcrumed on a rod 63 paralleling the shaft 48 and have extensions 59', 60' positioned to coact with a cam 64 on the shaft 19 of knob 18. The same shaft carries a laterally projecting arm 65 disposed to engage a camming ledge 66 on arm 40 when the latter is in its starting position at the right-hand end of screw 44 as viewed in FIG. 5. A switch 67, shown in detail in FIG. 6, is also mounted on stem 19. It comprises two cams 67a and 67b respectively co-operating with a pair of make contacts 68 and a set of switchover contacts 69. A source of alternating current, indicated schematically at 70, is connectable by the closing of contacts 68 to a bus bar 71 which leads to the drive motor 43 by way of cut-off switch 37 and contacts 69 in their normal position. A rectifier bridge 72 delivers direct current to a lead 73 which is connectable to the underground input terminal of motor 43 in the off-normal position of contacts 69 and is also connected to an amplifier 74 designed to energize the modulating coil 75 of cutting stylus 17 under the control of a microphone 76.

The mounting of cams 67a and 67b on shaft 19 is such that contacts 68 are open in the position of knob 18, being closed in all other positions thereof, whereas contacts 69 are ofi. normal only in position 2. Cam 64 depresses lever extension 59' during rotation of the knob into position 3, this operation coinciding with an engagement of ledge 66 by arm 65 to swing the arm 40 together with arm 39 horizontally toward lead screw 44 until the pin 53, lowered by the action of cam 64 upon lever 59, enters the small-pitch section 49. At the same time a stud 79 on tongue 51 depresses a somewhat resilient lever Stl which is hinged to arm 40 at 81 and has a slot 82 clearing the stem 38; as the rear extremity of lever 89 is articulated to link 23, this action lifts the weighted end of recorder arm 14, to the extent permitted by a stop collar 83 on stem 38 bridging the slot 82, and lowers its head 16 so that stylus 17 descends toward the platter 13. During the transition of the knob 18 from position 3 to position 4 the cam 64 first depresses lever extension 60' and thereafter partly releases lever extension 59, the resulting displacement of lever 60 urging the pin 57 into engagement with the large-pitch thread section 50. A separate groove 50 of like pitch, interleaved with groove portion 50, can be alternately engaged by pin 57; the provision of two or more interleaved grooves 50, 50 etc. in the large-pitch section of lead screw 44 facilitates the switchover into position 4 which can take place as soon as any of these grooves is aligned with pin 57.

In operation, knob 18 is turned from position 0 into position 1 to warm up the amplifier 74 while the platter 13 and the lead screw 44 are rotated ineffectually by motor 43. The user then switches to position 2 in which motor 43 is sharply braked by being supplied direct current from bridge 72. A disk 77 can now be deposited upon platter 13 to serve as a blank for the cutting of a record. Next, knob 18 is turned into position 3, this movement causing arm 65 to cam the lever 51 toward lead screw 44 which has resumed its rotation and whose helical groove 49 engages with its first turn the oncoming pin 53 now held depressed by the action of cam 64 on lever extension 59. This operation pro duces the starting turn 73a (FIG. 1) of a spiral groove cut into the disk 77 by the stylus 17 which, by the action of cam 64, has been pressed down onto the disk surface before arm 65 went into action. The system is now ready to receive, via microphone 76, an acoustic message to be recorded by means of the modulated main portion 78b of the cut groove. The main groove portion is produced as long as the recording arm 14 is advanced under the control of transport arm 40 whose pin 53 rides in the groove 49 of small pitch. If the message is of standard length, its termination will just slightly precede the transition of pin 53 from thread portion 49 to thread portion 50 which greatly accelerates the swing of arm 14 and causes the cutting of the lead-off portion 730 of the cut groove. This acceleration actuates the switch 37 in known manner to cut off the operation of the system by stopping the motor 43.

If the user desired to terminate the cutting of the groove 77a, 77b, 77c prematurely upon the recording of a relatively short message, he switches into position 4 whereby pin 57 is caused to engage groove 50 or 50 and to advance the recording arm 14 directly under the control of arm 39. Cam 64 in this position disengages the pin 53 from groove portion 49 but still maintains lever 59 sufliciently depressed to hold the stylus 17 with the necessary force against disk 77. The accelerated swing of arm 39 and, hence, of recording head 161 inscribes a final turn 780 of somewhat larger radius than in the previously described operation and actuates the switch 37 to stop the motor.

When the knob 18 has been reset to its 0 position, cam 64 affords increased play to lever 59 whereby the recording arm 14- can be readily lifted off the disk 77 and returned to its starting position alongside the platter 13. The cycle may then be repeated with another blank.

It will be apparent that the system shown in the drawing could also be operated with position 4 of knob 18 slightly advanced so that cam 64 still maintains the lever 59 fully depressed, thus keeping pin 53 engaged, while pin 57 takes over the radial drive of the recording head 16. In this case it will be desirable to make the link 23 and/or its connections somewhat flexible to facilitate the necessary divergence of the arms 39 and 40, it being understood that such divergence will not materially reduce the pressure exerted upon head 16 in view of the aforementioned resiliency of lever 80. While this solution simplifies the switchover from pin 53 to pin 57, it also entails a certain increase of background noise in the cutting of the terminal groove portion.

I claim:

1. In a sound-recording mechanism including a cutting head and a rotatable platter adapted to hold a blank, said head having means for cutting an acoustically modulated spiral groove in said blank, the combination therewith of a lead screw having a thread divided into a smallpitch section and a large-pitch section, drive means for concurrently rotating said platter and said lead screw, a support for said head pivotable about an axis substantially parallel to that of said platter whereby said head is generally radially displaceable across said blank, coupling means selectively engageable with said small-pitch section and said large-pitch section, and link means between said coupling means and said support for advancing said head across said blank under the control of said coupling means upon rotation of said lead screw.

2. The combination according to claim 1 wherein said support comprises a rotatable shaft, a block carried on said shaft, a stud traversing said block, a yoke straddling said block while being swingable on said stud in a plane including the axis of said shaft, and resilient means urging said yoke into contact with respective sides of said block.

3. The combination according to claim 2 wherein said block is provided with a bore transverse to said stud and traversed by the latter, further comprising an elastic member seated in said bore and bearing laterally upon said stud.

4. The combination according to claim 3 wherein said elastic member is a silicone pad.

5. In a sound recording mechanism including a cutting head and a rotatable platter adapted to hold a blank, said head having means for cutting an acoustically modulated spiral groove in said blank, the combination therewith of a lead screw having a thread divided into a small-pitch section and a large-pitch section, drive means for concurrently rotating said platter and said lead screw, a support for said head pivotable about an axis substantially parallel to that of said platter whereby said head is generally radially displaceable across said blank, a first coupling element engageable with said thread for consecutive displacement by said small-pitch section and said large-pitch section upon rotation of said lead screw, a second coupling element engageable with said large-pitch section only, selector means for engaging either of said coupling elements with said lead screw, and link means between said coupling elements and said support for advancing said head across said blank under the control of one of said coupling elements in engagement with said lead screw.

6. In a sound-recording mechanism including a cutting head and a rotatable platter adapted to hold a blank, said head having means for cutting an acoustically modulated spiral groove in said blank, the combination therewith of a lead screw having a thread divided into a small-pitch section and a large-pitch section, drive means for concurrently rotating said platter and said lead screw, a support for said head pivotable about an axis substantially parallel to that of said platter whereby said head is generally radially displaceable across said blank, a first coupling element engageable with said thread for consecutive displacement by said small-pitch section and said largepitch section upon rotation of said lead screw, a. second coupling element engageable with said large-pitch section only, selector means for engaging either of said coupling elements with said lead screw, link means between said second coupling element and said support, and spring means effective upon a disengagement of said second coupling element from said lead screw for urging said second coupling element into contact with said first coupling element whereby said support is displaced through the intermediary of the second coupling element under the control of said first coupling element in engagement with said lead screw.

7. The combination according to claim 6 wherein said first and second coupling elements are a first and a second arm swingable in planes parallel to said lead screw about the pivotal axis of said support and provided with exten sions deflectable toward said lead screw for engagement with said thread, said link means including a shaft rigid with said second arm and coupled with said support.

8. The combination according to claim 7 wherein said support includes a coupling member connected with said shaft for swingable movement in a substantially vertical plane including said pivotal axis, said link means further comprising a lever fulcrumed and articulated to said bracket and coupled with the deflectable extremity of said first arm for controlling the swing thereof in said vertical plane.

9. The combination according to claim 8 wherein said coupling member is a yoke, said support further including a block carried by said shaft and straddled by said yoke, a stud traversing said block and forming a fulcrum for said yoke, first resilient means urging said yoke into contact with respective sides of said block, and second resilient means in said block bearing laterally upon said stud.

10. The combination according to claim 7 wherein said deflectable extensions are resilient tongues provided with longitudinal slots and with thread-engaging means slidably carried in said slots.

11. The combination according to claim 10 wherein said tongues are provided with relatively offset humps, said selector means including lever means alternately engageable with said humps for depressing said tongues into contact with said lead screw.

12. The combination according to claim 11 wherein said selector means comprises a rotatable knob having cam means for actuating said lever means in different positions of said knob.

13. The combination according to claim 12 wherein said selector means further comprises additional cam means for displacing said first arm in its plane of swing toward said lead screw upon rotation of said knob from an inoperative into an operative position.

14. The combination according to claim 13 wherein said drive means includes an alternating-current motor, said selector means being provided with contacts for supplying direct current to said motor in said inoperative position and energizing it with alternating current in said operative position.

15. In a sound-recording mechanism including a cutting head and a rotatable platter adapted to hold a blank, said head having means for cutting an acoustically modulated spiral groove in said blank, the combination therewith of a lead screw having a thread divided into a smallpitch section and a large-pitch section, drive means for concurrently rotating said platter and said lead screw, a support for said head pivotable about an axis substantially parallel to that of said platter whereby said head is generally radially displaceable across said blank, a first coupling element engageable with said thread for consecutive displacement by said small-pitch section and said large-pitch section upon rotation of said lead screw, a second coupling element engageable with said large-pitch section only, selector means for engaging either of said coupling elements with said lead screw, cooperating cam means on said selector means and said first coupling element for displacing said first coupling element into initial engagement with said small-pitch section, and contact means controlled by said selector means for starting said drive means substantially concurrently with said initial engagement.

16. In a sound-recording mechanism including a cutting head and a rotatable platter adapted to hold a blank, said head having means for cutting an acoustically modulated spiral groove in said blank, the combination therewith of a lead screw having a thread divided into a smallpitch section and a large-pitch section, drive means for concurrently rotating said platter and said lead screw, a support for said head pivotable about an axis substantially parallel to that of said platter whereby said head is generally radially displaceable across said blank, a first coupling element engageable with said thread for consecutive displacement by said small-pitch section and said largepitch section upon rotation of said lead screw, a second coupling element engageable with said large-pitch section only, selector means for engaging either of said coupling elements with said lead screw, co-operating cam means on said selector means and said first coupling element for displacing said first coupling element into initial engagement with said small-pitch section, contact means controlled by said selector means for starting said drive means substantially concurrently with said initial engagement, link means between said second coupling element and said support, and spring means eifective upon a disengagement of said second coupling element from said lead screw for urging said second coupling element into contact with said first coupling element whereby said support is displaced through the intermediary of the second coupling element under the control of said first coupling element in engagement with said lead screw.

17. The combination according to claim 16 in which said head is provided with amplifier means for supplying modulating current thereto, said drive means comprising an alternating-current motor; said selector means including a knob having an off position and four alternate positions, first contact means for energizing said amplifier means in each of said alternate positions, second contact means for energizing said motor with alternating current in a first, third and fourth of said alternate positions and for supplying direct current to said motor in a second of said alternate positions, said cam means being operative upon transition from said second to said third alternate position, and control means for activating said first coupling element upon passage into said third position and for activating said second coupling element upon passage 10 into said fourth position. 

1. IN A SOUND-RECORDING MECHANISM INCLUDING A CUTTING HEAD AND A ROTATABLE PLATTER ADAPTED TO HOLD A BLANK, SAID HEAD HAVING MEANS FOR CUTTING AN ACOUSTICALLY MODULATED SPIRAL GROOVE IN SAID BLANK, THE COMBINATION THEREWITH OF A LEAD SCREW HAVING A THREAD DIVIDED INTO A SMALLPITCH SECTION AND A LARGE-PITCH SECTION, DRIVE MEANS FOR CONCURRENTLY ROTATING SAID PLATTER AND SAID LEAD SCREW, A SUPPORT FOR SAID HEAD PIVOTABLE ABOUT AN AXIS SUBSTANTIALLY PARALLEL TO THAT OF SAID PLATTER WHEREBY SAID HEAD IS GENERALLY RADIALLY DISPLACEABLE ACROSS SAID BLANK, COUPLING MEANS SELECTIVELY ENGAGEABLE WITH SAID SMALL-PITCH SECTION AND SAID LARGE-PITCH SECTION, AND LINK MEANS BETWEEN SAID COUPLING MEANS AND SAID SUPPORT FOR ADVANCING SAID HEAD ACROSS SAID BLANK UNDER THE CONTROL OF SAID COUPLING MEANS UPON ROTATION OF SAID LEAD SCREW. 